Helmets provide vital protection in numerous applications such as for members of the military, fire crews, police, and heavy industry. Because wireless communication is also essential, helmets provide a natural mounting location for the associated antennas because a helmet will be at the highest mounting point available on a human being. However, a projecting antenna in military applications increases a soldier's visual signature and thus increases the danger of sniper fire. Conformal antennas that do not project from a helmet tend to be quite narrowband, which interferes with defense objectives such as the Joint Tactical Radio System, which requires connectivity across a large bandwidth. Other concerns include the size and weight of the antenna, the antenna connection to the torso (assuming that the radio transceiver is carried on the torso), as well as heath issues resulting from the RF radiation. In addition, electromagnetic interference/electromagnetic compatibility (EMI/EMC) issues must also be considered for helmet-integrated antennas.
Given the concerns raised by helmet-integrated antennas, current military wireless applications have settled on body-mounted antennas. However, a body-mounted antenna will tend to interfere with other gear worn by a soldier. In addition, a body-mounted antenna will tend to be more obstructed such as when a soldier is in a foxhole or in a prone position. In contrast, a helmet-integrated antenna has the advantage of a higher, more rigid and stable mounting platform.
Accordingly, there is a need in the art for conformal helmet-integrated antennas offering high bandwidth and low RF radiation.